FUMIGATION OF CITRUS PLANTS. 15 
DARKNESS AND SHADE. 
The effect on plant injury of shade and darkness after fumigation 
is well illustrated by experiments 10, 12, 15, and 16 which are arranged 
in Table I for comparison of these influences. 
TaBLE I.—Comparative effects of diffused light and darkness on plants after fumigation 
with hydrocyanie acid. 
Postfumigation temperatures. 
Experiment 10. Experiment 12. Experiment 15. | Experiment 16. 
° ° ° 89°- 64°- ‘70°- 
Gorebpe ios Hen tGOcenh on 88°-90° F.2 63° F.2 91° F.1| 65° F. | 73° F. 
Darkness......- 2 2 Z 3 4 3 4 2 2 
Dinadiew. caoore: 2 2 2 3 4 3 4 2 2 
1 Includes 3 fumigation conditions. 
2 Includes 2 fumigation conditions. 
An examination of this table shows that in none of the several 
tests included is there any difference in injury between the plants 
placed in darkness and those placed in the shade following fumiga- 
tion. This condition holds equally true at the minimum post- 
fumigation temperature of 60° F. or the maximum of 91° F. for these 
experiments. Likewise this situation does not appear to be altered 
by the temperature of fumigation, for experiments 10, 12, and 16 
were performed at 61°-64° F. while experiment 15 was carried on 
at 86°-91° F. 
SUNSHINE. 
The influence of sunshine on citrus plants immediately after fumi- 
gation is clearly developed in experiments 10 to 19. Eight of these 
10 experiments show a decidedly greater injury to the plants placed 
in the sunshine after fumigation than to those placed in either the 
Shade or darkness at equivalent temperatures. This condition is 
brought out in Table IJ. 
TABLE II.—Comparative degree of injury between plants placed in the sunshine and those 
placed in the shade or darkness following fumigation. 
Postfumigation temperatures. 
Exp. | Exp.| Exp. Exp. | Exp. ; Exp. 
10,0} ties fig | EO ge a Exp. 18.? 19° 
° ° °o ° ° 70°— 70°- °o °o ° q 
797. 65°. ( 79° HR.) 80°. |85°R. | oe | ew. 85°-90° F. 87° F. 
Darkness. ......... | SARIS Seep ct ae i ace (ce te CI NSE ai exit a | Seah ee Ra | 
Stade ee Uno MaMa om ne tgs | 4 t.  | 8 
SUdISHING. 5s... 2. 4 4 5 4 5 4 4 4 Tyee a5) 5 | 
1 Experiment consisting of two distinct parts. 2 Experiment consisting of three distinct parts, 
